Enzyme inhibitors are found in almost all kinds of living organism and particularly in plants. Inhibitors in plants are often important for the regulation of certain metabolic reactions. In particular, lipase inhibitors are also widely found in plants, particularly plants such as cereals.
In the last two decades research into lipase inhibitors has been carried out to evaluate lipase inhibitors for use in obesity treatments, and commercial products based on lipase inhibition with the aim to treat obesity are known.
Within food and feed technologies, lipase inhibitors have not gained much focus. However, with the increased application and use of enzymes in the food and/or feed industries, more attention has to be paid to the effect of endogenous or added inhibitors to the food. WO 00/39289, for example, discloses novel xylanase inhibitors.
Lipases (E.C. 3.1.1.X) have also been used directly in the food and/or feed industries, for example in foods and/or feeds comprising cereals and, in particular in bread production. For instance, in EP 0 585 988 it is claimed that lipase addition to dough resulted in an improvement in the antistaling effect. It is suggested that a lipase obtained from Rhizopus arrhizus when added to dough can improve the quality of the resultant bread when used in combination with shortening/fat. WO94/04035 teaches that an improved softness can be obtained by adding a lipase to dough without the addition of any additional fat/oil to the dough. Castello, P. ESEGP 89-10 December 1999 Helsinki, shows that exogenous lipases can modify bread volume. Thus, lipases (E.C. 3.1.1.X) which hydrolyse triacylglycerols are known to be advantageous for use in the baking industry.
Some lipases in addition to having a triglyceride hydrolysing effect, are capable of hydrolysing polar lipids such as glycolipids, e.g. digalactosyldiglyceride (DGDG), and phospholipids (see for instance WO01/39602).
The substrate for lipases in wheat flour is 1.5-3% endogenous wheat lipids, which are a complex mixture of polar and non-polar lipids. The polar lipids can be divided into glycolipids and phospholipids. These lipids are built up of glycerol esterified with two fatty acids and a polar group. The polar group contributes to surface activity of these lipids. Enzymatic cleavage of one of the fatty acids in these lipids leads to lipids with a much higher surface activity. It is well known that emulsifiers, such as DATEM, with high surface activity are very functional when added to dough.
It has also been found that under certain conditions the use of lipases (E.C. 3.1.1.X) in dough may have detrimental consequences, such as the production of off-flavours, a detrimental impact on yeast activity, and/or a negative effect on bread volume. The negative effect on bread volume is often called overdosing. Overdosing can lead to a decrease in gluten elasticity which results in a dough which is too stiff and thus results in reduced volumes. In addition, or alternatively, such lipases can degrade shortening, oil or milk fat added to the dough.
Very little research work has however been done in relation to the lipase inhibitors in flour, particularly wheat flour.